Answer:
California and Oregon were admitted as new states.
Step-by-step explanation:
Given that California was admitted into the union in 1850 makes the option a wrong.
Also, Florida indeed became a part of the United States in 1821.
Similarly, the Louisiana Purchase indeed doubled the country's size. This was carried out in 1803.
And at the same time, New admissions indeed brought the total number of states to twenty-four. This was accomplished in 1821.
Hence, in this case, the correct answer is "California and Oregon were admitted as new states."